Single DIN In Dash

Since my old shaft style stereo doesn't work right, I got a nice little unit that's single DIN. AM/FM/CD/Bluetoof/AUX/USB....."all dat". I mean hell, I had to cut the dash a little for my old shaft style unit.....although it would be hidden with the original radio......but I figure screw it, I want something NICE and modern since this car is gonna be a cruiser. So here's my question. I cannot get my head around how the sleeve installs and secures in the dash hole. The instructions say something like "choose the appropriate tabs and bend them down to secure" or some such. I see the tabs, but I cannot get my mind around how that works.....since I've never done a conversion. I've worked on some that were already single DIN, just not converted older stuff. Can someone clear it up for me? A picture or three would really help.
You slide the "cage" into the dash opening, then the little tabs bend over, to the back side of the dash, to hold the cage.
The radio then slides and locks in, usually there is a stud or screw hole in the back side of the radio to hook a brace up to support the back of the radio.
Then the cover snaps on, to hide the "cage".
To remove the radio, you then have to remove the cover, and use the two supplied thin metal keys slide down the side of the radio to release it.